Fencing

What

Fencing off streams and wetlands from stock has many benefits. When livestock have free access to waterways it can cause stream banks to erode, releasing sediment into the water. Stock also pollutes the water directly with their excrement.

Why

The Resource Management Act (1991) was amended in 2017 to provide the Minister with the power to make regulations for the exclusion of stock from water bodies. These regulations specified streams more than a metre wide and deeper than 30 cm must be fenced to keep stock out of them.

Stock exclusion regulations are currently being revised as part of the Ministry for the Environment’s Essential Freshwater work programme. The stock exclusion regulations prohibit the access of cattle, pigs and deer to wetlands, lakes, and rivers. Read more about these requirements in Science – Legislation.

New Zealand scientific research published in the international Journal of Environmental Quality led by Dr Richard McDowell has found that smaller streams, less than 1m wide, actually account for the majority (77 %) of the contamination load in a catchment. This research states, “as a result, not requiring smaller streams to be fenced may simply be undermining efforts to stop declining water quality”.

Farmers who fence off streams improve the water quality, as the vegetation filters out nutrients and bacteria from farm runoff. The slowing of runoff also reduces flood peaks, which in turn reduces erosion of the stream bed. The overall improvement in water quality and cover along the stream margins improves the habitat for fish and bird life and this is enhanced if planting of shrubs is carried out in the riparian area.

Before and After photos of a creek that shows plant growth around the new fenced-off area.
Waterway vegetation prior to and after fencing.
Image source: TeAra

References

Bewsell, D., Monaghan, R. M., & Kaine, G. (2007). Adoption of stream fencing among dairy farmers in four New Zealand catchments. Environmental Management, 40(2), 201-209.

Collins, R., Mcleod, M., Hedley, M., Donnison, A., Close, M., Hanly, J., Horne, D., Ross, C., Davies‐Colley, R., Bagshaw, C. and Matthews, L. (2007). Best management practices to mitigate faecal contamination by livestock of New Zealand waters. New Zealand Journal of Agricultural Research, 50(2), pp.267-278.

Doehring, K., Clapcott, J. E., & Young, R. G. (2019). Assessing the functional response to streamside fencing of pastoral Waikato streams, New Zealand. Water, 11(7), 1347.

McDowell, R. W., Cox, N., & Snelder, T. H. (2017). Assessing the yield and load of contaminants with stream order: would policy requiring livestock to be fenced out of high-order streams decrease catchment contaminant loads? Journal of Environmental Quality, 46(5), 1038-1047.